The objective is to study the possible relationship of RNA tumor viruses to human prostatic cancer. The following approaches will be used: morphological, biological, immunological, and biochemical. Brignt-field, phase contrast, and fluorescence microscopy will be used to study tissues and cells from tumors and from their tissue cultures. Electron microscopy of original biopsy specimens and of their tissue cultures will be used to determine ultrastructure and to detect virus particles. Immunological studies utilizing complement fixation, immunodiffusion, immunofluorescence, mixed hemadsorption, and immunoferritin will be applied to specimens (benign and malignant) before and after tissue culture to demonstrate any virus-specific or virus-associated and/or tumor-specific antigens. Sera from patients with prostatic carcinoma and benign hyperplasia, and their relatives, will be tested against cells of their own tumors and extracts of the materials of their own and of other patients. Immune sera to animal tumor viruses will also be used. Biochemical and biophysical studies will be carried out for the presence of particles with properties similar to RNA tumor viruses of animals. Tissue culture fluids will be tested for reverse transcriptase activity and high molecular weight RNA. Various human cell cultures will be inoculated with prostatic cancer cell and their culture extracts for study of the presence of a virus. Cell cultures of prostate tissue will be inoculated with animal viruses or with human leukemic tissues for study of transformation and for virus rescue.